The presidential campaign is almost over, and it is clear that in at least two important respects the tricky relationship among the candidates, the press and the public has fallen short of what it should be.

First, it is a serious reflection on this political process that President Reagan has gone the entire campaign without a news conference.

His last such session with White House reporters was held on July 24. Since then, while Congress has finished its work, while important developments have taken place from the Philippines to El Salvador to Lebanon, he has stiff-armed the reporters who cover him. Reagan has been applauded for agreeing to two debates, but he has rejected an older obligation -- the obligation of a public official to answer in timely fashion the questions of the press and public.

The failing is not in the White House press corps, which has pressed aggressively and continually for news conferences. The failing is solely that of the president and his staff, who have arrogantly insisted that reporters be present when it suited their convenience -- as it did in shielding Reagan from a man- to-man debate with Walter Mondale -- and be kept at a distance when they were judged to be a risk or nuisance to this coddled chief executive.

One can only hope that voters understand the implications of this White House manipulation, and take it into account when judging the prospects for a full and free flow of information in a second Reagan term. A government that would so easily subvert the channels of public discussion during the three months of a presidential campaign is hardly likely to reopen them when it knows it will not have to face the voters again.

The other problem is in our business, and specifically among the television networks, which are stubbornly refusing to heed the pleas from voters and elected officials in the western states to slow down their election-night projections until everyone has had a chance to vote.

This issue came up in 1980, when NBC News announced almost three hours before the West Coast polls closed -- and slightly ahead of its competition -- that the presidential race was over and Ronald Reagan had won.

There was an uproar in the West, claims and counterclaims about the number of people who had been dissuaded from voting and the effect of the early projections on other close congressional and local races. There were hearings on Capitol Hill, a nonbinding resolution passed by Congress pleading with the networks to exercise a degree of self-discipline, and a good deal of commentary from other journalists -- including myself -- who thought that caution in using the exit polls to call an election before it is finished would be both prudent journalism and good citizenship.

But early this month, the three network- news executives made it clear that they are unpersuaded. They will, once again, use the exit polls to project each state's results as soon as its voting ends. And when enough states have been "projected," which could be as early as 5 p.m. western time, they will declare the presidential race decided.

All this is defended on journalistic principles of utmost piety, as if these organizations -- which routinely delay the transmission of their nightly newscasts to the West for three hours in order to maximize the audience and the advertising revenues -- were not driven by the most obvious commercial and competitive pressures.

Let it be said again: there is no reason why the American networks cannot do what the Canadians routinely do in their federal elections -- namely, activate the election-night networks by time-zone segments, starting in the east and moving west, and broadcast returns into each region only when its polls have closed. That way, viewers in the East are not delayed in getting results from their states, but voters in the West are allowed to participate in the most important act of democratic citizenship without being told their votes are moot.

Instead of agreeing to throw the switches in their control rooms as their Canadian counterparts do, the network executives insist that polling hours should be changed, or 24-hour voting instituted or, in the case of the new NBC news boss, that the Constitution be amended to eliminate the Electoral College and state-by-state voting for president, in favor of a direct national vote.

Frankly, I don't know which is worse -- the insistence by Reagan and his aides that he has no obligation to face the White House press corps from beginning to end of a presidential campaign, or the insistence by the television networks that they will race their computer projections onto the air, whether people have voted or not.

All I know is that the public is being poorly served by people who convert the Oval Office into a royal sanctuary and who use the public airways as their private playthings.